British Astronomical Association
	Meteor Section

1998 Leonids Meteor Shower

Vladimir Mester (Hornonitrianska Observatory, Slovakia)
1998 November 17 01.30-01.40 UT: 16mm fisheye lens, 35mm ISO1000 Kodak colour print film

Observing conditions were reasonably good on Nov 15-16, when several dedicated watchers were able to record low, but significant Leonid activity, of the order of 5-10 meteors/hr in the hours before dawn. A standout event - seen by many early-morning commuters - was a bright Leonid fireball over the southern UK in the pre-sunrise twilight at 06h45m UT. This turned out to be a foretaste of what was to come, and the following night, 1998 Nov 16-17 provided one of the most spectacular and memorable meteor displays for a great many years!

Following the 1998 February perihelion of the parent comet 55P/Tempel-Tuttle, it had been anticipated that a very strong Leonid display might occur around the time of Earth's closest passage to the meteor stream orbit's descending node at Nov 17d 19h UT. Historically, Leonid storms have occurred close to node-passage in the years following the comet's perihelion. Many parties of observers travelled to Asian longitudes in the hope of seeing a Leonid storm, or at least very high activity, around this time.

In the event, things turned out very differently from expectations! The highest activity from the Leonids in 1998 came some 16 hours ahead of node-passage, on the night of Nov 16-17. Observers in western Europe, including a great many of the BAA Meteor Section's regular contributors, enjoyed unexpectedly high rates, with bursts of 8-10 Leonids per minute being reported at times. Activity was at this high level by the time the radiant rose, around 22h45m UT, and stayed close to it until dawn at 06h UT. The highest rates of all, translating to sky- and radiant altitude-corrected Zenithal Hourly Rate (ZHR) about 280, were found around 01-02h UT. Around 06h UT, ZHR was still at least 220-250. Typical single-observer counts of 90-120 Leonids/hr have been reported by most reliable, experienced watchers. The high activity did fall off towards 12h UT, as indicated by reports from North America.

The 'plateau' of high rates was also marked by numerous bright events, including several fireball which lit up sky and ground, and left behind long-duration persistent train (some lasting for as much as 20 minutes after the meteor had gone!). Notable widely-seen fireballs over the UK included events at 00h15m, 00h51m, 01h31m, 03h45m (perhaps the biggest of all!), 04h29m, and 04h59m UT. The abundance of Leonids brighter than mag. 0 was remarkable, and also led to many photographers recording trails in large numbers.

Leonid activity had certainly tailed off from the bright meteor plateau by the time of node passage. Reports from the UK party which travelled to the India quote observed rates of around 40 Leonids/hr, which translate to approximate ZHR 100, well up on normal 'quiet-time' levels, but not as high as on the previous morning. Also, this activity was largely comprised of fainter meteors - perhaps more representative of the small meteoroids presumed to populate the enriched near-comet filament which has produced past storms. Few fireballs were evident over Asian longitudes on Nov 17-18, though observers there had seen some of the onset of the 'fireball peak' 24 hours earlier.

By radiant-rise over a largely cloudy UK on Nov 17-18, activity was well on the way down. The few available reports - mainly from Kent and East Anglia - show observed rates no better than 10-15 Leonids/hr.

Vladimir Mester (Hornonitrianska Observatory, Slovakia)
1998 November 17 03.05-03.20 UT: 80mm lens with wide-angle corrector, 6x6cm ISO400 Kodak colour film

Page last updated: 31/08/2005